Free tile servers for OSM basemaps

Lotssssss of free OSM basemap servers with previews to show how they look, most of which are free. This is for the contextily python library but all of them come with details for the XYZ tiles, for example:

url:	https://data.geopf.fr/wmts?SERVICE=WMTS&VERSION=1.0.0&REQUEST=GetTile&STYLE={style}&TILEMATRIXSET={TileMatrixSet}&FORMAT={format}&LAYER={variant}&TILEMATRIX={z}&TILEROW={y}&TILECOL={x}

Related: https://leaflet-extras.github.io/leaflet-providers/preview/